From streets to nightclubs, the collision of passion, adrenaline and flailing bodies has always been an aphrodisiac. It shouldn't be surprising then, that riots can get romantic from time to time.

Indeed, the recent evening of rage in Vancouver wasn't the first instance of a couple being caught, lips locked, in the midst of civil disobedience. In 1990, as the poll tax riots tore through central London, photographer David Hoffman captured this clinch in Trafalgar Square. "There was a tremendous feeling of warmth and togetherness," says Hoffman, who has been photographing protests for more than 30 years. "The woman was pregnant, and the man was arrested for affray a few hours later. This photo got him acquitted, as it proved he wasn't where the police said he was at the time."

Was he surprised to see a similar image from Vancouver? "Not at all. There's something about riotous situations that feels like all the normal rules have gone."